Centrifugal pellet dryers of both vertical and horizontal type are well known in the state of the art and include an outer housing, a screen oriented in the housing and a bladed rotor mounted in the screen for moving a slurry of fluid and pellets within the screen, to enable a discharge of fluid through the screen. A slurry inlet is provided along with two outlets for fluid and dried pellets. Centrifugal pellet dryers of the vertical type are disclosed in U.S. Pat. Nos. 3,458,945; 4,565,015; 4,896,435; 5,245,347 commonly owned by Gala Industries, Inc. In the operation of such dryers an exhaust fan as a blower at the upper end of the housing communicates directly with the interior of the dryer with the dryer rotor shaft extending upwardly from the dryer and being connected with the bladed rotor, so that the fan of the blower and the bladed rotor are driven by the same motor. The blower produces a countercurrent flow of drying air through the pellet discharge outlet duct.
One problem of such pellet dryer is to optimize the pellet discharge through said outlet duct since a varying amount of pellets are bounced back in an transition area between the end of the screen and an outlet opening in a side surface of the inner wall close to the vertical end of the housing in respect to the main rotational speed of the motor of the bladed rotor optimized in respect to an upward accelerating of the pellets by the blades of the rotor, which dictates contemporary the amount of the countercurrent flow of drying air provided by the main blower in a countercurrent direction to the upward accelerated pellets which is difficult to balance in an optimized way for both, the optimization of upward acceleration of pellets and optimization of drying the pellets by an optimized air flow. Actually there is an amount of pellets which has to be recycled since the pellets have not reached the outlet opening close to the vertical end of the housing.